Research And Development Of Silicon Carbide Based High Voltage Digital Direct Current Solid State Power Controller In Aeronautics Applications

Solid State Power Controller(SSPC)is a key device applied in modern aircraft automatic power distribution system,which has more advantages in maintainability,expansibility,reliability and automation compared with traditional Circuit Breaker(CB).Most existing SSPC adopt Si MOSFET.However,with the development of semiconductor devices,SiC-based SSPC is expected to improve its power density by reducing heater’s capacity and weight.This thesis is dedicated to research on SiC-based aircraft high voltage direct current SSPC.Switching characteristics of SiC MOSFET are firstly analyzed,and switching waveforms after adding parasitic parameters are presented by detailed analysis of each stage.Quantitative analysis of the effect of parasitic elements on SiC MOSFET switching performance is carried out by double pulse test.Based on this,a layout method based on parasitic inductances is proposed and verified by experiments.To improve the current rating of SSPC,current distribution characteristics of SiC MOSFET are investigated.Usually extra components or strategies are applied for compensation,which will highly increase the cost and the complexity of the system with more MOSFETs in parallel.Influences of device parameters,driver resistance and layout parasitic inductances on static and dynamic current distribution are studied without extra compensation circuits.A design method is deduced to achieve instant current balancing by use of parasitic inductances which has been verified by LTSpice and experiments.Also,an iteration calculation method to predict current and temperature distribution among paralleled SiC MOSFET are proposed to avoid time consuming in traditional simulation.A digital high voltage SiC based SSPC used in aircraft prototype with 270 V output voltage and10 A current is built and tested in the lab to verify the feasibility of the proposed strategy.The experimental results are presented including the load compatibility under different load conditions,I2 T protection,overcurrent protection and short-circuit protection.Also,temperature rise in this prototype verifies the feasibility of the proposed electro-thermal distribution prediction method.